Low-Power Red Laser Treatment for Anisometropic Myopia Control in Children: A Contralateral Comparison Study

Abstract

Background: There are some uncertainties about the effect of low-power red laser treatment on myopia control for anisometropic myopia in children. To evaluate the effect and safety of low-power red laser treatment on refractive development for anisometropic myopia in children, a contralateral comparison study was conducted. Methods: The more myopic eye of child with anisometropic myopia was treated with low-power red laser treatment (LRL group), the other eye received no treatment other than the wearing of single-focus spectacles (SFS) (SFS Group). The LRL treatment was given at home under parental guidance for 3 minutes each time, twice daily with a minimal interval of 4 hours, 7 days per week, using an equipment that produces red laser of 650 nm wavelength at an illuminance range of roughly 1200-1800 lux and an energy of 0.60 mw for a 4-mm pupil (class I classification). Results: Among 51 included children, 44 (86.27%) completed the 3-months study, consisting of 15 girls (34.1%) and 29 boys (65.9%). After 3-months axial length (AL) and spherical equivalent refraction (SER) progression were -0.08 mm [95% CI (confidence interval), 0.11 to 0.06 mm] and +0.23 diopter (D) (95% CI, 0.13-0.33 D) for LRL group and +0.08 mm (95% CI, 0.05-0.11 mm) and -0.07 D (95% CI, -0.16-0.03 D) for SFS group. AL and SER progression between the groups varied by 0.17 mm (95% CI, 0.13-0.20 mm) and -0.30 D (95% CI, -0.42 to -0.18 D). There was no visible structural damage on optical coherence tomography (OCT) scans. Conclusions: AL growth, myopia progression, and anisometropia of the binoculars can all be slowed down by LRL treatment. Compared to SER progression, axial elongation is more accurate and simpler to monitor. LRL treatment unrecorded functional and structural damage of binoculus.

A retrospective study of cumulative absolute reduction in axial length after photobiomodulation therapy

“…Comparisons with previous randomized controlled trials (RCTs) of PBM therapy revealed both similarities and differences. Consistent with prior RCTs ( 14 , 15 , 16 , 17 – 18 ) significant AL shortening was observed within the first month. However, a notable departure was observed in the timing of maximum AL shortening.…”

“…However, a notable departure was observed in the timing of maximum AL shortening. Unlike previous RCTs ( 4 , 14 , 15 , 16 , 17 – 18 ), where maximum AL shortening occurred within the first 1–3 months [ 4 ], in this real-world data, the maximum effect occurred at both Month 6 and Month 12, with Month 6 exhibiting particularly pronounced results.…”

“…And neither the choroidal thickness changes nor the cornea curvature could fully explain the negative CARE; that is, AL shortening and myopia recession after weeks of therapy [ 23 ]. Experiments either from Jiang Y et al [ 17 ] reporting high illumination of 1600 lx or from Wang Y et al [ 18 ] reporting an illumination range of about 1200–1800 lx suggested that the inhibitory effect on myopia may be partly due to higher ambient illuminance, not totally due to the wavelength or the color red only. But it might be more than that, our previous illumination was only 400 lx to cause the similar effect [ 4 ].…”

Real World Study of Cumulative Absolute Reduction in Axial Elongation after Photobiomodulation Therapy

“…And neither the choroidal thickness changes nor the cornea curvature could fully explain the negative CARE; That is, AL shortening of myopia recession after weeks of therapy 20 . Experiments either from Jiang Y et al 21 with report the high illumination of 1600lux or from Wang Y et al 22 with report the illumination range of about 1200-1800lux…”